Refrigerator cabinet



Sheets-Sheet 1 J. c. RILL, JR.. E rAL REFRIGERATOR CABINET INVENTOR.John 6. R/'// Jr. BY Ke/fh K. Kes/mg Nov. 29, 1960 Filed Nov. 14, 19577' hair Affmey Nov, 29, 1960 J. C. RILL, JR., EIAL REFRIGERATOR CABINET2 Sheets-Sheet 2 Filed Nov. 14, 1957 INVENTOR. Ja/m 6. R/// Jr.

United States Patent-O REFRIGERATOR CABINET John C. Rill, Jr., and KeithK. Kesling, Dayton, Ohio, assignors to General Motors Corporation,Detroit, M1ch., a corporation of Delaware Filed Nov. 14, 1957, Ser. No.696,548

5 Claims. (Cl. 220-9) This invention pertains to refrigerating apparatusand especially to insulated refrigerator cabinets in which a foamedinsulation is cast within the walls.

Some modifications of the new foamed polyurethanes have insulationcharacteristics sufiicient to make possible low cost, thin walledrefrigerator cabinets having heat leaks lower than the present thickwalled cabinets insulated with glass. or mineral wool. These new foamedpolyurethanes have excellent adhesion properties, are low in Weight,high in structural strength for their weight, and have high insulatingproperties. However,-full advantage of these properties cannot beobtained by merely filling the insulation space of present cabinets withthese or other equivalent foamed materials.

It is an object of this invention to provide a refrigerator cabinetconstruction in which the insulating material foamed and cast within thewalls not only provides superior insulating properties but alsoeliminates structural parts and their assembly by serving as aninterconnecting structure binding together the inner and outer shell asa single structural unit.

It is another object of this invention to eliminate the complications ofthe conventional door seal and support arrangement and to provide asimple, resilient seal formed as an adjunct to the foam insulation.

It is another object of this invention to provide a simple, inexpensivemethod of making a refrigerator cabinet in which the extensive assemblyof many small parts and screws is eliminated and replaced by the castfoamed material having binding, structural and insulating properties.

It is another object of this invention to provide a simple method ofmaking refrigerator cabinets in which the mixture of liquids whichreacts to form the foam is introduced through the open back anddistributed throughout the insulation space while the liner and outershell lie face-down.

These and other objects are attained in the examples shown in thedrawings in which a film of flexible material extends across theintervening gap between and is bonded to the front edges of both aplastic box-shaped liner having a front opening and an outer shellhaving front and rear openings. The assembly is then placed with theflexible film and the front openings face-down so that it rests over asupport or mold upon the front edges. The support or mold may have acavity of the shape complementary to the form which it is desired thatthe cabinet have between the front edges of the liner and the outershell. Alternatively, an adherent film may be applied to the support ormold.

In this position there is introduced a mixture of material capable offorming a foamed synthetic elastomeric polymer of the polyester orpolyether class in an amount sufficient to form a resilient door sealupon the rear face of the adherent film extending between the frontedges of the liner and outer shell. After this material has foamed andset, there is also applied to this elastomer a thin layer of polyvinylalcohol. After this polyvinyl ICC alcohol has set, there is introducedthrough the open back of the outer shell a mixture of materials whichwill form a semi-rigid or rigid foamed polyurethane having highstructural insulation and adhesion properties sufficient in amount tofill the remainder of the space and to cover the back of the liner to asufiicient depth to provide adequate insulation. A back cover ispreferably applied immediately after introduction of the mixture. Thechemical reaction causes the urethane foam to expa'nd to the inner faceof the back panel to which is adheres and retains in place aftersolidification. After it sets, the foamed material will support theliner and the back panel in place without any assistance and theelastomeric material will form a resilient surface between the film andthe rigid insulation which will form a seal with the contacting surfaceof the door when the door is closed. The joint between the back coverand the outer shell is sealed with polyvinyl alcohol to seal theinsulation.

. Further objects and advantages of the present invention will beapparent from the following description, reference being had to theaccompanying drawings, wherein a preferred form of the present inventionis clearly shown.

In the drawings:

Figure 1 is a front perspective view of a refrigerator cabinet embodyingone form of my invention;

Figure 2 is a fragmentary enlarged sectional view taken substantiallyalong the line 2-2 of Figure 1, with the door in closed position;

Figure 3 is a front diagrammatic perspective view of the liner and shellin the position in which the film 0f flexible material is applied to thefront edges of the outer shell and inner liner;

Figure 4. is. a perspective view showing the second step of the assemblywith the liner and outer shell face-down upon a support showing theintroduction of the insulation material;

Figure 5 is a perspective view of the back of the cabinet;

Figure 6 is a fragmentary horizontal sectional View of a rear corner ofthe cabinet; and

Figure 7 is a similar fragmentary horizontal sectional view of amodified rear corner construction.

it is well known that a wide variety of polymeric materials such aspolyesters, polyesteramides, polyalkylene glycols, castor oil and othermaterials having a plurality of reactive hydrogen groups may be reactedwith organic polyisocyanates in the presence of accelerators and/orcross linking agents to produce foamed polyurethane plastics which mayhave a density ranging from about 1 to 20 lbs. per cu. ft. and arevaluable for use as insulation and structural material. The formation ofpolyurethane plastics involves a series of complex physical and chemicalreactions wherein heat is evolved and the cellular or foamed characterthereof results from the formation and evolution of carbon dioxide gasin the cour e of the reaction as a consequence of a reaction be tweenthe carboxyl andisocyanate groups and/or between water and isocyanategroups. Foamed or cellular plastice of this type are described in, forexample, the US. Patents 2,764.565, 2,772,245, 2,642,403 and 2,639,252.

7 Since a major portion of the volume of a polyurethane foam suitablefor use as insulation material consists of voids filled with carbondioxide gas, it is apparent that the effectiveness of the insulation isto a large extent dependent on the coelficiency of thermal conductivityof the carbon dioxide gas or other gas contained in the voids of theinsulation material.

Although several preferred examples of such material are specified inthe following specification, the invention is not limited thereto butextends to their equivalents essence as an example, includes an outershell 20 which may be of metal, plastic or other suitable materialhaving a r desirable exterior finish such as porcelain or other types ofenamel or lacquers. The outer shell preferably is rectangular in shapeand has a top and sides and a portion 22 extending beneath the storagecompartment door refrigerant to the condenser 26. These are located offto the side in Fig. 1, but actually will be located beneath theinsulation of the storage compartment behind the portion 22. Thecondenser 26 is connected by a small capillary conduit to the evaporator28 located in the storage compartment 30 provided with numerous shelvesopening behind which is the motor-compressor condenser unit, showndiagrammatically as the motor-compressor 24 for compressing therefrigerant and forwarding the and storage drawers which are supportedby the inner liner 32.

The inner liner 32 may be of either metal or plastic provided with aporcelain or other enamel coating, if desired, and may have wallprotrusions specially formed to support the shelves and drawers. Theshell has a transverse bottom wall 34 immediate above themotorcompressor and condenser 24 and 26. As shown in Fig. 2, the spacebetween the inner liner 32 and the outer shell throughout is filled witha suitable high structural strength light-weight foamed plastic material46, preferably of the polyurethane class. Particularly, a rigid orsemi-rigid, odorless polyurethane foam having a density of 1 /z-2 /2lbs. per cu. ft., a yield point in compression of 20 to 30 lbs. per sq.in. having 90% closed cells, and a coeflicient of thermal conductivityor k factor at 70 4 opening or door itself. Such a door seal is usuallymechanically fastened by screws and clips or other devices alsorequiring considerable assembly time.

According to this invention, the resilient door seal is provided by aresilient elastomeric foam layer 50 provided on the front edge of theinsulation 46 and bonded thereto with the polyvinyl alcohol layer 49 inbetween, both extending completely around the door opening. This layer,50 at the center is preferably of a thickness of about /2" and has aresiliency sufficient to permit a. deflection or impression of the headinto it at a pressure of from 9-18 ozs. for each foot of the bead 48.For example, if the head 48 should be A" wide, this would mean adeflection force of 3 ozs. per sq. in., while if the width of the bead48 is this would require a force of 6 ozs. per sq. in. to achieve thedeflection or impression of the bead 48. This elastomeric foam layer 50is preferably of the formulation set forth as Example A in the latterportion of the specification but may also be a latex foam or Examples 1or 2 of Patent 2,764,565 issued September 25, 1956.

This elastomeric foam layer 50 is preferably covered by a thin, flexiblefilm 52 of polyester or other vapor barrier film which is attached by asuitable polyester or other suitable adhesive to the adjacent edgeportions of the inner liner 32 and the outer shell 20, as is shown inFig. 2. As an alternative, the layer 50 may be provided with an adherentabrasion and moisture resistant decorative film of chlorosulfonatedpolyethylene or polyvinyl chloride. Also, if desired, a metallizedpolyester film or a laminated synthetic resin sheet material may be usedfor the flexible film 52. Preferably, this laminated material includesone layer of a synthetic resin which is a conof from .1 to .16B.t.u.-in./hr.sq. ft.-- F. as deter- ,1

as Examples 1, 2 and 3 in the latter portion of this specification.

To seal this insulating material 46 and particularly to prevent anyescape of the halo derivatives of the aliphatic hydrocarbons thereinwhich might reduce its insulating properties, the exposed surface iscoated throughout with a thin layer 49 of polyvinyl alcohol which issubstantially alcohol which is substantially impermeable to suchderivatives. This layer 49 extends from and bonds with the inner liner32 to and bonding with the outer shell 20 and all the intervening areabetween the insulation 46 and the elastomer 50 hereinafter described.This layer 49 bonds to both the insulation 46 and the elastomer 50throughout.

The door 36 which closes the compartment 30 has an outer shell 38 ofmetal or plastic which may be coated with porcelain or other enamel, andan inner panel40 of plastic or metal which likewise may be coated withporcelain or other enamel. The outer door shell 38 may have anoverlapping joint 42 with the inner door panel 40. The interior of thedoor 36 may be filled with the same foamed polyurethane insulationmaterial 44 as the material 46 between the liner 32 and the outer shell20. The inner panel 40 is provided with a bead 48 extending toward theinsulation 46 entirely around the periphery of the door 36. The door 36may be provided with a conventional latch, not shown.

The foamed polyurethane material 46 provides all the necessary supportof the inner liner 32, thus making unnecessary the usual breaker stripsordinarily applied in four sections connecting the inner liner and outershell by many screws. It is also customary to provide a resilient doorseal extending around either the door? densation product of ethyleneglycol and terephthalic acid popularly known by the trade name Mylar. Onboth sides of this layer is applied a thin coating of polyvinyl alcoholwhich, in turn, is coated with a layer of polyethylene. This serves asan effective barrier to water, moisture and gases but this film 52 maybe omitted if its functions are adequately served by the surface skinupon the layer 50.

The back 66 of the cabinet preferably is separate from the outer'shell.It may have a simple offset edge 74 overlying and overlapping theinturned rear flange 70 of the outer shell 20 as in Fig. 6, providing asimple overlap joint. Or, as in Fig. 7, a tongue-in-groove joint may beprovided. In this form, the inturned rear flange 72 L of the outer shell20 has at its inner edge throughout a deep groove 73. t

-In Fig. 7, th e back 66 has throughout its perimeter an inwardly turnedright angle flange or tongue 76 extending into the deep groove 73 of theflange 72. This groove 1 73 is preferably filled with polyvinyl alcoholwhich forms sealed throughout with polyvinyl alcohol extendingbedeveloped for making this refrigerator.

tween the offset edge 74 and the flange 70.

Particular examples of the formulation of the materials 44,46 and 50, asmentioned heretofore, are specified in the following description of thepreferred process In this process, the'box-shaped inner liner 32 withthe front side open is supported within the outer shell in uniformlyspaced relation by a suitable fixture or by four blocks 56 locatedbetween the corners of the liner 32 and the outer shell 20, as shown indotted lines in Fig. 3. The flexible film 52 previouslyspecified is thenlightly stretched across the front edges of the inner liner 32 and theouter shell 20 and fastened by a suitable polyester or other adhesive toboth edges; If desired, this'film and the step of attacl1-, ing it maybeomitted, as previously suggested. After the adhesive has set, theassembled liner 32 and outer shell 20 are placed fac'edouin 'up'onlthemold or support 58 which may be either flat or have a suitablerectangular groove into which the flexible film 52 may extend to providewhatever shape may be desired. Preferably, this groove may have acontour substantially complementary to the contour of the film 52 or thesurface of the clastomeric layer 50 shown in Fig. 2, With the exceptionof the depression caused by the penetration of the head 48. If the film52 is omitted, a spray film of chlorosulfonated polyethylene orpolyvinyl chloride is applied to this groove to form a decorativeabrasion and moisture resistant film which will adhere to the layer 50.

The outer shell 20 has no back, as yet, upon it and therefore the backis entirely open. Its rear edge has a narrow inturned flange 70 as shownin Fig. 6. An alternate form of flange 72 with an outwardly facing deepgroove 73, is shown in Fig. 7. As the first step in the facedownposition, the fixture or blocks 56 may be removed through the open back.The synthetic elastomeric foamed material is supplied from the mixingnozzle 60 which is traversed over the film 52, or over the spray film inthe groove of the support 58 within and entirely around the spacebetween the inner liner 32 and the outer shell 20 to provide the layer50 in the thickness previously specified.

Example A This material forming the layer 50 preferably is a resilientelastomeric polyurethane foam which can be made from such compounds asare formed in the mixing nozzle 60 by the reaction of the followingcomponents. A prepolymer is formed by the combination of toluenediisocyanate 80% 2,4 isomer, 20% 2,6 isomer, and a polypropylene glycoland heat under anhydrous conditions. After cooling, the prepolymer isthen reacted with an emulsifier such as an organo-silicone polymer, acatalyst such as N-methyl morpholine and water. These materials aresupplied separately through the flexible conduits 62 and 64 andhomogeneously mixed in the mixing nozzle 60. The mixing nozzle isintroduced through the opening in the rear of the shell 20 and thematerial issuing therefrom is applied to the rear face of the flexiblefilm 52 all around the front opening of the liner 32 until the material50 is built up to a suflicient thickness of the elastomeric foammaterial to admit of a deflection with a pressure of 9-18 ozs. perlineal ft. of the head 48. Instead of this particular compoundedmaterial, there may be substituted the material described in Examples 1and 2 of Patent 2,764,565 issued September 25, 1956, a latex foam orother equivalents.

After this elastomer 50 is set, ontoits upturned or rear face there isflowed or sprayed a solution of polyvinyl alcohol which may be made asfollows:

Forty grams of polyvinyl alcohol powder are mixed cold with 480 gramswater until blended. This mixture is heated to 200 F. and stirred for 20minutes and then cooled to 120 F. To this mixture is added a mixture of160 cc. of isopropyl alcohol and 160 cc. of water. The resultingsolution is heated to 120 F. To a solution of 160 cc. water and 40 cc.isopropyl alcohol there is added 1.6 grams of Congo Red. This islikewise heated to 120 F. and the two resulting solutions mixed and at atemperature of 120140 F. are flowed or sprayed onto the elastomer 5iInstead of the isopropyl alcohol, there may be substituted methyl, ethylor normal propyl alcohol. Instead of the Congo red gelling agent, theremay be substituted borax, gallic acid, alpha-naphthal, resorcinal,benzopurpine or the sodium salt of either salicylanilide, orbetanaphthal salicylanilide or disalicylbenzidine.

Over this layer of elastomeric foamed material forming the resilientdoor seal 50' and the polyvinyl alcohol layer 49, there is applied thefoamed insulation material 46. This is cast in between the liner 32 andthe outer shell 20 While they remain in the position shown in Fig. 4.After the material forming the foamed insulating material 46 is insertedin between the. inner liner 32 and outer shell 20, the back 66 isapplied and firmlyheld in place. This back 66 may have several smallperforations 77 to permit the escape of excess insulating material 46.After the insulating material 46 has solidified, it firmly holds theback 66 in place. The excess insulating material which has passedthrough the escape perforations 77 is removed and the perforations 77 aswell as the joint between the edges of the back wall 66 and the flanges70 or 72 are sealed by a liquid flow application of the polyvinylalcohol solution referred to with respect to the layer 49. This isflowed along the edge of the back 66 in Fig. 6. In Fig. 7, the polyvinylalcohol solution is flowed into the deep groove 73 to seal the flange 76throughout. While many foamed materials can be used in the insulationspace, because of their high structural strength, high insulating valueand low weight and their excellent adhesive properties, the polyurethanefoams are the most desirable of the materials available at the presenttime.

One example of the polyurethane foamed insulation may be mixed ofcomponents which lead to the production of polyurethane plasticsaccompanied by an evolution of carbon dioxides.

Example 1.An ethylene glycol-adipic acid polyester was prepared having ahydroxyl number of about 440, an acid number of about 1.5 and a watercontent of about .5 by weight. A portion of the polyester was reactedwith an isocyanate mixture consisting of about 80% by weight 2,4 toluenediisocyanate and 20% by weight 2,6 toluene diisocyanate to produce apolymer having an isocyanate equivalent of about .80 per grams of theisocyanate-modified polyester. The isocyanate-modified polyester wasplaced in a tank and a mixture of 60 parts by weight of the ethyleneglycol-adipic acid polyester, .25 part of dimethyl ethanolamine, 2.5parts by weight of water and 1.5 parts by weight of polyoxyethylenesorbitan monopalmitate as an emulsifier was placed in a second tank. Thetwo components were separately supplied through the conduits 2, 64 tothe. mixer 60 having a rotor rotated at about 3,000-5,000 r.p.m. andmixed at a ratio of 63.75 of the latter to 100 parts by weight of theformer to produce a carbon dioxide blown foam having a density of about2 lbs. per cu. ft. and initial coeificieut of thermal conductivity or kfactor at 70 F. of about .157 B.t.u.-inch/hr.-sq. ft.F. as determined bythe guard ring hot plate method. Due to leakage, this coeflicientincreases and eventually stabilizes at the range of .22-26.

However, as preferred examples, the production of the insulationinvolves components which, when mixed, produce polyurethane plasticswhich on reaction are not accompanied by any substantial evolution ofcarbon dioxide nor any gaseous product having a coeflicient of thermalconductivity similar to or greater than that of carbon dioxide. Instead,a liquid blowing agent is used which is evaporated by the heat of thereaction and has an appreciable lower thermal conductivity than carbondioxide. The components mixed involve a first polymeric component orresin containing reactive hydrogen groups other than carboxyl groups inappreciable amounts, a second component which is an organicpolyisocyanate, and a third component which promotes the reaction andmay include cross linking and accelerating agents other than water.

Examples of suitable polymeric components include polyesters such as thereaction product of adipic acid and polyethylene glycol having a verysmall or negligible acid number. Various polyesters or polyesteramideswhich may be used for the production of polyurethanes of the presentinvention may be obtained by condensing a variety of poly-basic acids,preferably dibasic acids such as adipic, sebacic, phthalic, oxalic,malonic, succinic, maleic, fumaric, itaconic, etc., with polyalcoholssuch as ethylene glycol, diethylene glycol, glycerol, sorbitol and/oramino alcohols such as ethanolamine and aminoade'aies propanol. Alkyleneglycols and polyoxyalkylene glycols which may be used include ethyleneglycol, propylene glycol, styrene glycol, diethylene glycol,polyethylene glycol, polypropylene glycol and copolymers of theseglycols. A high-grade castor oil having a very small or negligible acidnumber may also be used.

Examples of suitable organic polyisocyanates include aromaticdiisocyanates such as toluene 2,4 diisocyanate, toluene 2,6 diisocyanateand mixtures thereof, naphthalene 1.5 diisocyanate and M-phenolenediisocyanate. Various polyisocyanates referred to in the patents setforth in this specification may also be used.

Examples of components promoting the polyaddition reaction of the firsttwo mentioned components to provide an essential acceleration of thereaction include ethylethanolamine, diethylethanolamine, pyridine,hexahydrodimethylaniline, methyl piperazine, dimethyl piperazine,tribenzylamine, N-morpholine and K-methyl morpholine.

The components referred to above may be modified in a variety of ways toproduce a reacting mixture leading to the production of solidpolyurethane plastics not accompanied by the evolution of substantialamounts of carbon dioxide or other gaseous products. component may beinitially reacted with the polyisocyanate to form apolyisocyanate-modified polymer having a predetermined percentage offree isocyanate groups or a predetermined percentage of hydrogenreactive groups. In the latter case, it is necessary to include crosslinking or chain extending components having reactive hydrogen groupssuch as ethylene glycol, into the reaction. Components such astrimethylol propane, polypropylene glycol, polyethylene glycol, or apolyester having a very small or negligible acid number may be utilizedfor this purpose. The essential character of a suitable formulation inaccordance with the present invention is that the components selectedlead to the formation of solid polyurethane plastics without anappreciable evolution of carbon dioxide gas.

The preparation of the foamed polyurethane insulation of the presentinvention involves the introduction of the components leading to theformation of polyurethane plastics referred to above into an enclosedmixing zone substantially simultaneously with the introduction of aliquid which will vaporize as a consequence of the heat generated by thereacting component and having desirable thermal properties in a gaseousor vapor state. The following are examples of polyurethane foamssuitable for the insulation 44 and 46. The components may be introducedthrough one or more flexible conduits connecting with a mixing nozzleidentical or similar to the conduits 62 and 64 and the mixing nozzle 60.To introduce these components through the flanged opening in the rearwall of the shell 20, the nozzle is traversed around the space betweenthe inner liner 32 and the outer shell 20 and thence traversed over theupwardly turned rear Wall of the liner 32 until sufficient material isintroduced which, when completely foamed, will fill the entireinsulation space. Immediately after this, the back 66, which may be ofmetal or plastic or suitably treated fibreboard, provided with suitablesmall escape apertures is placed on the'back of the shell 20 and held inplace until the foaming and setting of the material is sufficientlycomplete. This back 66 is supported by the flanges 70 or 72 extendingaround the rear edge of the outer shell 20 as in Figs. 6 or 7 and haseither the offset edge 74 as in Fig. 6 or the inwardly turned flange 76extending into the deep groove 73. Specific formulations follow.

Example 2.--An ethylene glycol-adipic acid polyester was prepared havinga hydroxyl number of about 430, an acid number of about 1.50 and anegligible water content. A portion of the polyester was reacted withthe toluene diisocyanate to produce an isocyanate modified polyesterhaving an isocyanate equivalent of about .80 per 100 grams of theisocyanate-modified polyester. A mix- Thus, the polymeric ture of 100parts by weight of the above mentioned isocyanate modified polyester,.50 part by weight of polyoxyethylene sorbitan monopalmitate, and 30parts by weight of trichloromonofluoromethane (F-ll) was placed in atank and kept cool, such as below 50 F. A mixture of 60 parts by weightof the ethylene glycol-adipic acid polyester, 12 parts by weight ofethylene glycol, .25 part by weight of dimethyl ethanolamine and .25part by weight of polyoxyethylene sorbitan monopalmitate emulsifier wasplaced in another tank. The components from the two tanks were suppliedseparately through the conduits 62, 64 to the mixer 60 and mixed asbefore at a ratio of 130.50 parts by weight of the former to 72.50 partsby weight of the latter. The mixed components issuing from the mixer 60were deposited in the insulation space between the inner liner 32 andthe outer shell 20. After two minutes the temperature of the reactingmixture rose to about 250 F. and a foamed product was produced in theinsulation space having a density of about 2 lbs. per cu. ft. and havinga k factor at 70 F. of about .100 B.t.u.-inch/hr.-sq. ft.-- F. asdetermined by the guard ring hot plate method.

Example 3.-The process of Example 2 was repeated utilizingtrichlorotrifluoroethane (F-l13) having a boiling point of about 118 F.instead of the trichloromonofluoromethane (F-11) to produce a foamstructure having a k factor at 70 F. of .100 B.t.u.-inch/hr.--sq. ft.-F. as determined by the guard ring hot plate method.

It is apparent that the foaming of the material described in the aboveExamples 2 and 3 results in the main from the vaporization of the liquidtrichloromonofluoromethane (F11) or the trichlorotrifluoroethane (I-113) respectively due to the exothermic heat of reaction. Other liquidssuch as dichloromonofluoromethane (F- 21), monochloroethane,monchloromonofluoroethane (F- 151a), monochlorodifluoroethane (F-l42a)and trifiuorodichloroethane (F-133e) having boiling points ranging from48 F. to F. and coefficients of thermal conductivity substantially lessthan that of carbon dioxide, may also be used. These materials do nothave a tendency to appreciably retard the reaction rate as does sulphurdioxide, for example, and they vaporize readily in the process due tothe heat generated in the reaction. Further, these materials are inertso that they may be fed into the reaction mixture either in admixturewith one of the polyurethane components as illustrated in the aboveexample, or separately.

It is, of course, understood that various details of construction,styling and materials may be changed, substituted and modified withoutchanging the essential character of the invention in which the principalfeatures are the support of the inner liner and the door seal solely bythe insulation and the absence of the usual breaker strips andmechanical support of the door seal.

While the embodiment of the invention as herein disclosed constitutes apreferred form, it is to be understood that other forms might beadopted, as may come within the scope of the claims which follow.

What is claimed is as follows.

1. A refrigerator cabinet including an outer shell having an open side,an inner liner within and spaced from said outer shell and having itsopen side aligned with the open side of said outer shell, said shell andliner having their edges spaced adjacent said openings, a relativelyrigid closed cell type polyurethane foam material having the voidsfilled with a gas having low thermal conductivity between said shell andliner and extending between and terminating between said edges, aresilient elastic closed cell polyurethane foam material overlying andbonded to the terminating surfaces between and adjacent said edges, theexposed surface of said resilient material having bonded thereto andbeing covered by a thin flexible vapor barrier film extending over andbeing bonded to the exposed surfaces of said inner liner and outer shelladjacent said resilient material, and a door for closing said open sidehaving means extending adjacent its periphery for engaging saidresilient elastomer for sealing the door to the insulation.

2. A refrigerator cabinet including an outer shell having an open side,an inner liner Within and spaced from said outer shell and having itsopen side aligned with the open side of said outer shell, said shell andliner having their edges spaced adjacent said openings, a cellular typethermal insulation between and bonded to said shell and liner having itscells containing a halo derivative of an aliphatic hydrocarbon, a thinlayer of polyvinyl alcohol extending over the entire face of saidinsulation extending between said shell and said liner to seal saidinsulation to prevent the escape of said derivative, a resilientelastomer overlying throughout and bonded to said layer of polyvinylalcohol, a water vapor barrier film extending over said elastomerbetween said shell and liner, and a door for closing said open sidehaving means extending adjacent its periphery for engaging said filmupon said resilient elastomer for sealing the door to the insulation.

3. A refrigerator cabinet including an outer shell having an open side,an inner liner within and spaced from said outer shell and having itsopen side aligned with the open side of said outer shell, said shell andliner having their edges spaced adjacent said openings, a cellular typerigid polyurethane thermal insulation between and bonded to said shelland liner having its cells containing a halo derivative of an aliphatichydrocarbon, a thin layer of polyvinyl alcohol extending over the entireface of said insulation extending between said shell and said liner toseal said insulation to prevent the escape of said derivative, aresilient elastomer overlying throughout and bonded to said layer ofpolyvinyl alcohol, a water vapor barrier film extending over saidelastomer between said shell and liner, a door for closing said openside having means extending adjacent its periphery for engaging saidfilm upon said resilient elastomer for sealing the door to theinsulation, an outer rear wall separate from said outer shell, andpolyvinyl alcohol sealing the joint between said outer rear wall andsaid outer shell.

4. A refrigerator cabinet including an outer shell having an open side,an inner liner within and spaced from said outer shell and having itsopen side aligned with the open side of said outer shell, said shell andliner having their edges spaced adjacent said openings, a cellular typethermal insulation between and bonded to said shell and liner having itscells containing a halo derivative of an aliphatic hydrocarbon polyvinylalcohol sealing said cellular insulation in the space between said linerand said outer shell, and a water vapor barrier extending over saidpolyvinyl alcohol between and sealing the space between said shell andliner.

5. A refrigerator cabinet including an outer shell having an open side,an inner liner within and spaced from said outer shell and having itsopen side aligned with the open side of said outer shell, said shell andliner having their edges spaced adjacent said openings, a closed cellpolyurethane foam insulation having a fluoro halogenated aliphatichydrocarbon gas of low heat conductivity contained within said cells,said foam being coextensively bonded to the inner surfaces of the outershell and the inner liner with a strong permanent bond for adding to thestructural strength of the cabinet and for positively sealing thecontiguous surface of the foam against ingress or escape of gastherethrough, a continuous sealing layer of polyvinyl alcoholcoextensively applied to the surface of said foam between said edges andto the junction of the foam with said edges for positively sealing saidsurface against ingress or escape of gas therethrough, and a door fordoing said open side having means extending adjacent its periphery forsealing the door to the insulation.

References Cited in the file of this patent UNITED STATES PATENTS1,952,528 Bedford Mar. 27, 1934 2,091,335 Roberts et a1. Aug. 31, 19372,106,840 Gould Feb. 1, 1938 2,234,847 Swedman Mar. 11, 1941 2,346,566Ford Apr. 11, 1944 2,502,581 Morrison Apr. 4, 1950 2,552,641 MorrisonMay 15, 1951 2,653,139 Sterling Sept. 22, 1953 2,787,809 Stastny Apr. 9,1957

